MEASUREMENT AND VALIDATION OF DYNAMIC BENDING STRESSES IN SPUR GEAR TEETH

摘要

New steels and novel manufacturing processes require the accurate determination of design allowable stresses for the purpose of optimum gear design. Although many methods are employed to establish the bending strength of spur gear teeth, most rating methods are similar in their simplicity and do not realistically account for dynamic conditions. Various static tests have been used in the past to confirm gear designs and rating capabilities but, generally, do not account for realistic dynamic effects. Tests performed on a power re-circulating test rig are the closest to actual operating conditions as experimentally possible. However, careful calibration of the measurement instrumentation is essential to obtain accurate results. The motivation for this investigation was to accurately measure the dynamic stresses on spur gear teeth with a carefully calibrated power re-circulating test rig. This paper describes the procedure undertaken to measure and characterize the bending stresses experienced at the gear tooth root fillet, during power transmission on a power re-circulating test rig and presents the results obtained. Emphasis was placed on obtaining accurate results using strain gages and digital data acquisition equipment. The data presented in this paper demonstrates the stress state, in a gear tooth under load, with a degree of fidelity that is unavailable in current literature. Additionally, dynamic strain waveforms were rigorously analyzed for repeatability and correlation to the physical phenomenon of a gear tooth mesh to validate the measurements, with significant success. The paper also compares the experimentally obtained stresses to expected values calculated from several existing rating methods.